It is known that a fusion reactor does not only produce helium and energy from the fusion of deuterium (D) and tritium (T), but also certain impurities resulting in particular from the reaction of the plasma with the first wall or any other reactor component. It is thus necessary to withdraw this gas from the plasma at regular periods and to purify it. The gas can be contaminated by a great number of impurities. In combination with light water, heavy water or tritiated water, these impurities may consist of sulphur compounds such as SO, SO.sub.2, (H,D,T).sub.2 S, tritiated hydrocarbides such as C.sub.n (H,D,T).sub.2n+m, mainly methane, as well as N.sub.2, O.sub.2, CO, CO.sub.2.
The purification methods known until now and described for example in the report "Los Alamos 6855-P" by J. L. Anderson and R. H. Sherman, in June 1977, entitled "Tritium System Test Assembly", are fairly complicated and expensive and require in certain subsystems a rise of the temperature of the gas containing the tritium up to values at which the tritium migrates into the metals of the apparatus and passes therethrough due to its permeation capacity.
The invention provides for a simpler method which does not imploy high temperatures for the tritiated gases and which may be realised in a simple and compact device. This latter feature is well appreciated for reasons of security and of reducing the quantity of radioactive material present in the device. It further results therefrom that only a simple, small and cheap system of dynamic confinement is necessary for the normal or abnormal purification conditions, due to the reduced space necessary for its operation. This reduces considerably the costs of investment and renders economic the extraction and the processing of the plasma.